Typical systems for determining and controlling ventilation within a building or a room (zones) are based on maximum occupancy of the building or room or by using a counter to count the number of individuals present. Basing ventilation on maximum occupancy of the building or room often uses more energy than is required—because often times the building or room is not at capacity—and, therefore, reduces the lifetime of the equipment. Furthermore, these systems often use carbon dioxide (CO2) sensors to determine the total amount of CO2 in a building or room. In addition to the cost of the CO2 sensors, they also require periodic checks to ensure that they are reporting correctly. A technique for providing demand control ventilation with increased ability meet the demands of the occupants and/or with reduced initial setup cost, hardware cost, and overhead is desired.